What is a load box?

When using a tube amplifier, you should always connect it to a speaker cabinet before turning it on – or a loadbox. The speaker cabinet (2, 4, 8 or 16 Ohms) must always be connected to the corresponding speaker output of your amplifier. Not doing so can lead to partial or complete destruction of the output stage of the tube amplifier. Most tube amp designers protect their products with fuses etc, but some amps do not have sufficient protection in place. Our general moto is that “It is impossible to predict the behavior of all the amplifiers on the market in case of use without a load (a speaker cabinet or a load box)”.

The electronic term that describes the speaker cabinet with respect to the amplifier is the “load”: we say the cabinet “loads” the amplifier. The term “load box” fits any product that embeds an electronic load. The main parameter of the load box is its impedance, and that is rated in “Ohms”. An 8-Ohm load box must be plugged to the 8-Ohm speaker output of the amplifier.

When using a Torpedo load box, the power sent to the load is turned into heat, so please follow the cooling recommendation of the load box – failure to do so may cause overheating which can lead to damage, both to the load box and to the amplifier. The Torpedo Reload, Live, Studio, Captor and Captor X are load boxes. This term indicates that these products feature a load which can electrically replace the speaker cabinet while safely dissipating (transforming into heat) the power coming out of the amplifier.

The embedded load in the Torpedo products is reactive: it embeds a specific circuit to simulate the complex impedance of a real speaker. This kind of system is widely used in the industry to silently test amplifiers.

Is the use of a loadbox totally silent?

We usually talk about “silent recording” when a load box is involved. If we compare the load box solution to a traditional cabinet miking solution, it is obviously several orders of magnitude quieter, but you will still experience some minor sounds, noises, that have to be taken into account:

Your guitar or bass strings can be heard. This is obvious, but it can be disturbing, depending on your environment if you are not used to it.

You may hear some noise coming out of your Torpedo when playing, like there is a tiny speaker inside the box. This is perfectly normal and there is no reason to worry. The sound is produced when power goes through the coil of the reactive load embedded on the Torpedo. The vibration is related to what power comes out of the amplifier connected to the Torpedo and to the signal’s frequency content (notes played are heard). Your amplifier may also produce similar noise, at the output transformer’s level. Such noise is usually not heard, simply because it is normally overcome by the sound coming from the loudspeaker.

The Torpedo embeds a fan, as there is quite a lot of power dissipated into heat inside the box. We selected a “silent fan”, but as it is running fast, it is never entirely silent. This said, you can consider that, in normal use (hearing your guitar through monitors, or headphones), you can barely hear that fan.